broad-leaved dock vs sour grass

broad-leaved dock and sour grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
broad-leaved dock	Yes	No	No	No
sour grass	Yes	No	No	No

As nouns, sour grass is a hypernym of broad-leaved dock; that is, sour grass is a word with a broader meaning than broad-leaved dock:

broad-leaved dock: European dock with broad obtuse leaves and bitter rootstock common as a weed in North America
sour grass: any of certain coarse weedy plants with long taproots, sometimes used as table greens or in folk medicine

Other hypernyms of broad-leaved dock include dock, sorrel.

broad-leaved dock (noun)	sour grass (noun)
European dock with broad obtuse leaves and bitter rootstock common as a weed in North America	any of certain coarse weedy plants with long taproots, sometimes used as table greens or in folk medicine